The present invention generally relates to a method and apparatus for setting building support columns within a foundation. The present invention more particularly relates to a method and apparatus which provides a secure footing for a support column, where the column may be installed after a concrete floor has been completed rather than the current practice of installing the column and pouring concrete around the column.
It is known in the construction industry to set vertical columns, such as steel columns typically utilized in the construction of various structures, within concrete footings. One known method of preparing the footing for a column is to set a group (usually four) of L-shaped anchor bolts within a first concrete footing member, with threaded ends of the anchor bolts extending above the top of the first footing member, where a nut is disposed on the threads of each anchor bolt. The first concrete footing member typically has steel reinforcement. A flat slab (or section of slab) comprising the floor of the structure is poured after the L-shaped bolts for each of the columns of the structure have been set within a column's respective first footing member. However, forms are constructed around each column footing to isolate the column footing from the slab, forming an area hereinafter referred to as the “blocked out area.” The first footing member and the group of upwardly facing anchor bolts within the blocked out area remain exposed after the slab has been poured until later in the construction process as described below.
Once the first concrete footing member around each group of L-shaped anchor bolts has cured, columns having a baseplate attached to the bottom end of each column are attached to the upwardly extending ends of the L-shaped anchor bolts at each footing location. Typically, nuts are first made up on the threads of the L-shaped anchor bolts prior to placing the baseplate and column over the bolts such that the baseplate comes to rest against this first group of nuts as the baseplate is disposed on the anchor bolts and the column set in a vertical orientation. A second nut is thereafter made up on each anchor bolt thereby securing the baseplate to the footing.
Upper structural members or roof members are thereafter attached to the columns. The column and baseplate are leveled as necessary and the space between the first concrete footing member and the bottom of the baseplate is filled in with grout known as “dry pack.” An inspection of the column footing is normally required after the baseplate has been grouted.
Once the grout underneath the baseplate has adequately cured, concrete is typically poured into the blocked out area overlying the first footing member, thereby forming a second layer of concrete around the column base and footing. The pouring of the cement slurry in the blocked out area around the column usually occurs after the roof or upper floor structural members have been set in place, often making it difficult to bring large equipment in to pour the cement slurry in the blocked out area. The second layer of concrete surrounds the steel column and completely covers the baseplate and the upwardly extending ends of the L-shaped bolts. The level of the second layer of concrete is generally flush with the surrounding concrete slab.
The method described above for affixing columns to a concrete foundation has some disadvantages. For example, the second layer of concrete in the blocked out area surrounding the columns is visually distinct from the rest of the slab. The boundary lines created by the forms between the surrounding slab and the second concrete layer are clearly visible. Moreover, because of the time span between the pouring of the slab and the second concrete layer, there is a color variation between the concrete slab and the second concrete layer. In structures such as a warehouse, where the slab is not covered with floor coverings, the visible difference between the slab and the concrete adjacent to each column are not as aesthetically pleasing as for a slab surface constructed with a single pour.
As another disadvantage, the pouring of the second concrete layer in the blocked out area requires mobilizing equipment for mixing, delivering, and pouring the concrete. The mobilization of the equipment can be further complicated because of the addition of new members to the structure, such as wall members or roof members, which reduce access of equipment to the blocked out area. It is often necessary to utilized wheel barrows to transport concrete slurry to the blocked out area, resulting in an increase in the time required to pour the second concrete layer.
As another disadvantage, the known system can result in delays while waiting on inspections or waiting for equipment to arrive. For example, an inspection of the dry pack around the bottom of the column is normally required before the second concrete layer can be poured.
An apparatus and method which allows the pouring of the concrete slab and the second concrete layer around the column footings in a single pour would eliminate or reduce the visible differences between the slab and the second concrete footing, reduce mobilization time for concrete equipment, and reduce waiting time required for inspections or equipment. An apparatus and method which enables the baseplate to be leveled without grout would eliminate the time involved in placing the grout, allowing it to set and waiting for inspection.